My red hair washed out after 4 days. I only washed it twice. I'm a natural looking medium reddish brown now. I LOVED the red day one. It was awesome, and I'm, sad that it happened.
I did, however, learn a valuable lesson: IF YOU WANT TO BE RED GET YOUR HAIR COLORED BY A PROFESSIONAL. That was very capslock Harry Potter a la book five, but it's the truth. Don't play.